Holding means for test specimens



D. c. SCOTT 2,32 7,139

` HOLDING MEANS FOR TEST SPE-CIMEN Aug. 1W'j E943.

Filed DeG. 30, 1942 INVENTOR ATTORNEYS Patented Aug. 127,

U-Ni'1fau` STATE HOLDING MEANS FOR. TEST SPCIIENS David C. Scott,Providence, It. I., assignor to Henry L; Rhode Island Scott Company, acorporation of t Application December30,1942,' Serial No. 470,554

4 claims. (o1. 265-12) This invention relates tothe testing o! flexible'materials such as tapes, webbing, cord or other flexible like materials,the ends of which must be gripped for applying tension thereto intheperformance of the test. A y

In `performing a tensile test upon a flexible material it is diilicultto obtain the proper grip upon the materialso that the samef'will notslip' or become misaligned during the test. It has been proposed toprovide twovjawls one of.which is movableand to position an end of the.material to be tested between the jaws and then wrapthe material aboutthe jaws-so that the pull of the.`

material will move one of the jaws toward the other and rmly grip thematerial Iwhich is located between the jaws. In order that the pull onthe material being't'estedmay be free from' the ,material which iswrapped about the fixed jaw differentl expedientshave been resorted toto accomplish this purpose, such for instance as making the fixed jawsmaller than the movable jaw so that the material being tested as itleaves the movable jaw will clear the fixed jaw. This arrangement whilesatisfactory from the standpoint of clearance does not always positionthe .25

' line of pull directly through th center line of the specimen able.

One of the objects of the invention is to provide a clamp in which thepulling of thespecimen serves to hold thejaws of the clamp firmly uponthe specimen and to properly align thespecimen with reference to thepull thereon.

when under test which is' also desir- Another object of this inventionis to so mount the clamp that the line of pull will be directly throughthe center of the specimen and the' specimen will also leave one of thejaws at such` location as to clear the other jaw and the part of thespecimen wrapped thereabout.

Another object of this invention is to providea pair of such jawsbetween which the specimens extend so mounted that when a pull isapplied through the jaws to move the jaws ,directly away v from eachother the jaws vwill rock to locate the specimen so4 supported that itwill extend along the line of the pull with the pull extending`substantially through the center of the specimen regardless of itsthickness. l

Another object of lthe invention is to provide an arrangement forclamping the specimen initially which clamp may be removed as the testproceeds.'

With these and other objects in view, the invention consists ci certainnovel features of construction,A as will vbe more fully described andparticularly pointed out in the appended claims.

In the accoxripanyingl drawing: 1 y Fig. 1 is a top planview showing thevtest specimen as supported by two of my improved clamps with tensionapplied to the clamp supports to locate the clamp in the relativeposition assumed while tension is applied; s

Fig'. 2 is'an elevation of one of the main clamps alone;

' Fig. 3 is an end view of the clamp shown-in Fig. 4 with the auxiliaryclamp in place;

Fig. 4-is a central sectional view. oi the clamps shown in Fig. 2 withthe auxiliaryl clamp in dotted lines: v

Fig. 5 is a detailed view of the auxiliary clamping means for holdingthe jaws in initial gripping i position; and

Fig. 6 is anelevation illustratinga machine in which the-clamps aremounted.

The testing machines in which my clamps are used are any of thewell-known types of testing machines for testing the tensile strength oftextile materials. The horizontal type machine such as illustratedherein may be found in the testingv machine ol Patent No. 1,911,006dated A May 23, 1933, or No. 2,205,579 dated June 25, 1940,

although it will be appreciated that the arrange- `ment of clamps suchas shown herein may be clisv posed vertically if desired.

The test specimen designated I0 is heid at each of its end portions byclamps designated gener ally Il and I2, one of which may be held and theother of which may be moved so as to apply tension on the specimen orboth may be movable a load may be applied. The support for one clamp isdesignated I3 and the support for Athe otherclamp i4 and in thearrangement here shown the Y support l! is moved by some power meanssuch for instance as a thread shaft I5 while the support t3 is heldfixed against movement.

The ends of these supports I3 and I4` are threaded as at 20 and the bodyportion 2| pro- 40 vided with a threaded socket 22 is screwed onto thesupport I3 or il as may bedeslred. This body is reduced (see Fig. 4) toprovide a stud 23 through which a pin 24 extends which is headed andprovided with a cleat at one end and is threaded as at 25 at the otherend. Member 26 is pivotally mounted upon the stud 23 and is held againstescape from the stud by a washer 21 held i snugly against the end of thestud by the nut 28 screwed on to the pin 24'. 4The thickness ofl thecollar of the member 2E is less than the length of'the stud so that ithas vfreedom oi motion about the stud in a pivotal relation. However,

there extends stops 28 and 3.0 from the body 2| which will be engaged bya pin 3i on the member '2 8 to limit the pivotal movement of the member26 about the stud 23.

6o tant from the pivotal mounting 23 is halt round 3Gl is slidablyguided in this slot whilea .plate 3l attached as at 38 to the undersideof the jaw 35 prevents the jaw from being lifted upwardly as seen' inFig. 4 out of the slot 35. This jaw 35 may move toward the jaw 32 bysliding along the slot 35 which extends in line with the center of thepivot of the studf 23 and the center of the arc of the rounded fixed jawy33. This movable `jaw also has a rounded surface 33 substantially onthe arc of a circle and a fiat surface 39 which is on a diametrical linesubstantially through the center of the arc of the rounded surface 38.This flat surface 39 is roughened or serrated by means of notches 4I] soas to provide a better holding surface for the end of the specimen whichis placed between the jaws to be engaged by the surfaces 34 and 39. -Itwill'be apparent that the rounded surface 33 is of a smallervradius thanthe rounded surface 38.

To load the specimen into the device the two clamps are broughtsufciently close together so that theV ends of the specimen may bereadily fed into each of the clamps. One end of the specimen I which isdesignated 4I is passed through a slot 42 in the'fixed jaw and theredoubled upon itself as as 43 (see Fig. 1). The specimen is then ledbetween the gripping surfaces 34 and 39 as at 44 and then wrapped aroundthe curved surface 33 of the xed jaw as at 45, then about the curvedsurface 38 of the movable jaw as at 46 (see Fig. 1) and then to theother clamp where a similar disposition of ythe end portion of thespecimen to be tested is provided to secure it in position in thecompanion'clamp. The pull on this specimen is directed along the line ofthe supports I3 and I4 and the center of the pivots upon which themembers l26 of the clamps are mounted are 'in this line of pull thus thecenter of the studs 23 are in the line of the pull along the supports I3and I4. As the pull commences the member 26 will rock about the pivots23 until the specimen I 0 is disposed along the center of pull throughthe suppoits I3 and I4 and the pivots 23 for the members 26. Thus all ofthe pull is directed through the center of the specimen. The members 26rock so' as to provide for this while at the L same time it will beapparent that the specimen l0 leaves the clamp I I at a. tangentdirectly below the' center of the pivot of the clamp so that thespecimen pulls free from contact with any other part of the specimenwhich is wrapped around `the jaws in order that the directed pull maycause the movable jaw to more firmly pressthis movable jaw toward thefixed jaw without any retarding friction and firmly grip the part of thespecimen designated 44 which is between the jaws. By this arrangement avery rm grip on the end portion of the specimen is had and the greaterthe pull the greater the grip to hold the specimen fixedly in position.

It is apparent, however, that prior to the exerting of some pull uponthe specimen it is desirable to clamp the jaws together and accordinglyI have provided a pair of arms 45 and 46'with a screw 41 freelyrotatable in an opening 48 in the arm 45 and threaded into an opening 49in the arm 46 by means of an abutment head 50. Another screw 5I has anend 52 abutting the larm 45 while it is threaded through opening 53 inthe arm 45. The screw may be moved by reason of a handle 54. This clampis positioned n the hollow portions and 56 of the jaws and the jaws areinitially held together until tension upon the specimen commences thenthese auxiliary clamps may be removed or may be left in place as desiredfor the remainder of the test.

I claim:

1. In a testing machine, a clamp support, a member pivotally mountedthereon, a clamp carried by said member at a point spaced from saidpivot mounting Aand comprising xed and movable jaws, saidfixed `iawbeing distant from said pivotal mounting and the movable jaw beingmovable toward and from the, fixed jaw whereby the'specimen to be testedmay be positioned between the jaws of the clamp and Wrapped about thefixed jaw and then about the movable jaw to extend toward a means tohold the other end so that when tension is applied through the saidsupport the member will rock to dispose the specimen toward the line ofpull through said pivotal mounting.

2. In a testing machine, a clamp support, a member pivotally'mountedthereon, a clamp carried by said member at a point spaced from saidpivot mounting and comprising xed and movable jaws, said xed jawbeingdistant from said pivotal mounting and ther movable jaw beingmovable along a line between the fixed jaw-and pivotal mounting towardand from the fixed jaw along a line between the fixed jaw and pivotalmounting whereby the specimen to be tested may be positioned between thejaws of the clamp and wrapped about the fixed jaw and then about themovable jaw to extend toward a means to hold the other end so that whentension is applied through the said support the member will rock todispose the specirrien toward the line of pull through said pivotalm'ounting.

3. In a testing machine, clamp supports each having a pivot, a membermounted to rock on each of said pivots, and a clamp carried by each ofsaid members at points spaced from said pivots each clamp comprising ahalf round jaw fixed on the outer end of the member and a half roundmovable jaw movable toward the fixed jaw whereby the specimen to betested may be positioned between the jaws of a clamp and wrapped aboutthe xed jaw and then about the movable pull between said pivots.

4. In a testing machine, a clamp support, a member plvotally mountedthereon, a clamp carried by said member at a point spaced from saidpivot mounting and comprising fixed and movable jaws, said xed jaw beingdistant from said pivotal mounting and the movable jaw beingmovable'toward and from the fixed jaw whereby the specimen to be testedmay be positioned between the jaws of theclamp and wrapped about theA:fixedl jaw and then about the movable jaw to extendgtoward a means tohold the other end so that when tension is applied through the saidsupport the member will rock to dispose the' specimen toward the line ofpull through said pivotal mounting and means to initially clamp the jawstogether upon the specimen.

Y DAVID C. SCOTT.

